Implication of asymptomatic and clinical Plasmodium falciparum infections on biomarkers of iron status among school-aged children in Malawi

Background Iron status is considered as a continuum from an iron deficiency with anaemia, without anaemia, varying amounts of stored iron to iron overload. The burden of Plasmodium falciparum infections is typically high among school-aged children (SAC). Nonetheless, SAC are often less likely to be covered by malaria interventions, making them a group with an untreated reservoir of parasite transmission. This study aimed to assess the effects of asymptomatic and clinical malaria infections on biochemical markers of iron status among SAC in Malawi. Methods Data from the 2015–2016 Malawi Micronutrient Survey (MNS) was used and multivariable logistic regression models using a generalized estimating equation to account for the complex cluster survey design were constructed. Blood samples of 684 children aged 5 to 14 years old were evaluated for clinical and asymptomatic malaria infections. Furthermore, blood samples were used to estimate haemoglobin (Hb), serum ferritin (SF) and, soluble transferrin receptors (sTfR) concentrations. Results Of the 684 SAC analysed, approximately 42% had asymptomatic malaria, while 41.0% had clinical malaria. Anaemia (low Hb levels), iron deficiency (low SF concentration), and functional iron deficiency (high sTfR levels) were found in 20%, 5%, and 30% of the children, respectively. School-aged children with asymptomatic malaria had increased odds of being anaemic (adjusted odds ratio [aOR]: 3.71, 95% confidence interval [CI]: 2.29–5.99) and increased levels of sTfR (aOR: 3.00, 95% CI 2.01–4.47). Similarly, SAC with clinical malaria had increased odds of being anaemic (aOR: 3.54, 95% CI 2.19–5.72) and increased levels of sTfR (aOR: 3.02, 95% CI 2.02–4.52). Conclusions Both asymptomatic and clinical malaria were independent risk factors for anaemia and functional iron deficiency (FID). The notion that asymptomatic and clinical malaria were associated with both anaemia and FID underscores the need for public health programmers to consider adding mass screening and treatment for malaria to existing school-based health programmes. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04297-1.

Hello. My name is _______________________________________. I am working with The National Statistical Office (NSO). As part of the Demographic and Health Survey we would like to ask you some questions about some of the foods that you may have in your home. We are particularly interested in learning more about salt, sugar and oil. If you agree we would like to take a very small sample of any of these foods that you have, so that we can test whether or not they have been fortified with vitamin A or iodine. In exchange we will replace any items you have given us. This information will help the Ministry of Health understand better what foods people have in their homes and the quality of the foods.
Do you have any questions? You can say yes or no. It is up to you to decide. Will you allow us to talk to you about some foods you may have in your home? In the past 4 weeks (30 days), was there ever no food to eat of any kind in your house because of lack of resources to get food?
How often did this happen in the past 4 weeks (30 days)?
In the past 4 weeks (30 days), did you or any household member go to sleep at night hungry because there was not enough food?
How often did this happen in the past 4 weeks (30 days)?
In the past 4 weeks (30 days), did you or any household member go a whole day and night without eating anything at all because there was not enough food?
How often did this happen in the past 4 weeks (

CHILD'S SEX
As part of this survey we are asking a parent of some children to allow us to weigh and measure their children and check them for Oedma. If your child has severe acute malnutrition we will refer your child to the nearest facility that can help you. In addition to weighing and measuring your child we would like to take a sample of his/her blood and urine. The tests are safe. Some tests may cause your child slight discomfort, such as taking a blood sample. For all tests, there will be a brand new set of equipment used to take your child's blood and collect their urine, which is clean and completely safe. The equipment will be thrown away after it has been used on your child. With the blood we will test your child for anemia and malaria. Anemia is a serious health problem that usually results from poor nutrition, infection, or chronic disease. Malaria can also be serious and can lead to your child becoming anemic or making the anemia worse. You will be given these results immediately. If needed your child will be referred to a local health facility for treatment. The rest of the blood will be sent to a laboratory to be tested for other vitamins and minerals, such as vitamin A and iron. The results from these tests will not be reported back to you as it will take some time to process the blood.The results will be kept strictly confidential. This information will help the Ministry of Health understand better what problems children in Malawi are experiencing and help them to improve the health and nutrition programs here, which will benefit all children in Malawi.
CHECK 208: AGREED FOR BLOOD TEST Has (NAME OF CHILD) had a fever in the last 24 hours?
Has (NAME OF CHILD) been ill with malaria in the last 2 weeks?
Has (NAME OF CHILD) had a fever in the last 2 weeks?
Has (NAME OF CHILD) had a cough or breathing problems in the last 2 weeks?
In the last six months, has (NAME OF CHILD) received a blood transfusion?
At what time approximately did (NAME OF CHILD) eat her/his most recent meal or was breastfed?
Have you noticed blood in (NAME OF CHILD)'s urine in the past 2 weeks?
In the last month, has (NAME OF CHILD) received a vitamin A capsule?
Has (NAME OF CHILD) had diarrhea in the last 2 weeks?  '3','5',CODE '3','5',CODE '3','5',CODE '3','5',CODE '3','5',CODE '3','5','6' OR '7' 6' OR '7' '6' OR '7' 6' OR '7' '6' OR '7' 6' OR ' As part of this survey we are asking some people to participate in an additional test. We would also like to include your child in an additional test to find out more information about vitamin A in the body. This test will involve giving your child a small amount of liquid to swallow with a snack. We will then have to wait about 4 hours and then take an additional small blood sample.
The results from this test will help the Ministry of Health understand better how well the food fortification program in Malawi is working and if other improvements are necessary. As part of this survey we are asking a parent of some children to allow us to weigh and measure their children and check them for Oedma. If your child has severe acute malnutrition we will refer your child to the nearest facility that can help you. In addition to weighing and measuring your child we would like to take a sample of his/her blood and urine. The tests are safe. Some tests may cause your child slight discomfort, such as taking a blood sample. For all tests, there will be a brand new set of equipment used to take your child's blood and collect their urine, which is clean and completely safe. The equipment will be thrown away after it has been used on your child. With the blood we will test your child for anemia and malaria. Anemia is a serious health problem that usually results from poor nutrition, infection, or chronic disease. Malaria can also be serious and can lead to your child becoming anemic or making the anemia worse. You will be given these results immediately. If needed your child will be referred to a local health facility for treatment. The rest of the blood will be sent to a laboratory to be tested for other vitamins and minerals, such as vitamin A and iron. The results from these tests will not be reported back to you as it will take some time to process the blood.The results will be kept strictly confidential. This information will help the Ministry of Health understand better what problems children in Malawi are experiencing and help them to improve the health and nutrition programs here, which will benefit all children in Malawi.

PURPLE TOP TUBE (EDTA)
In the last month, has (NAME OF CHILD) received any therapeutic foods, such as PLUMPY NUT [CHIPONDE]?
In the last month, has (NAME OF CHILD) received a vitamin A capsule?
Has (NAME OF CHILD) had a fever in the last 2 weeks?
Has (NAME OF CHILD) had a fever in the last 24 hours?
Has (NAME OF CHILD) had diarrhea in the last 2 weeks?
Has (NAME OF CHILD) been ill with malaria in the last 2 weeks?
Have you noticed blood in (NAME OF CHILD)'s urine in the past 2 weeks?
In the last six months, has (NAME OF CHILD) received a blood transfusion?
At what time approximately did (NAME OF CHILD) eat her/his most recent meal or was breastfed?
CHECK 208: AGREED FOR BLOOD TEST Has (NAME OF CHILD) had a cough or breathing problems in the last 2 weeks?
In the last six months, has (NAME OF CHILD) received deworming treatment?
In the last month, has (NAME OF CHILD) taken iron tablets/ syrups/ Multiple micronutrient powders?  As part of this survey we are asking some people to participate in an additional test. We would also like to include your child in an additional test to find out more information about vitamin A in the body. This test will involve giving your child a small amount of liquid to swallow with a snack. We will then have to wait about 4 hours and then take an additional small blood sample.
The results from this test will help the Ministry of Health understand better how well the food fortification program in Malawi is working and if other improvements are necessary. As part of this survey we are asking a parent of some children to allow us to weigh and measure their children and check them for Oedma. If your child has severe acute malnutrition we will refer your child to the nearest facility that can help you. In addition to weighing and measuring your child we would like to take a sample of his/her blood and urine. The tests are safe. Some tests may cause your child slight discomfort, such as taking a blood sample. For all tests, there will be a brand new set of equipment used to take your child's blood and collect their urine, which is clean and completely safe. The equipment will be thrown away after it has been used on your child.
With the blood we will test your child for anemia and malaria. Anemia is a serious health problem that usually results from poor nutrition, infection, or chronic disease. Malaria can also be serious and can lead to your child becoming anemic or making the anemia worse. You will be given these results immediately. If needed your child will be referred to a local health facility for treatment. The rest of the blood will be sent to a laboratory to be tested for other vitamins and minerals, such as vitamin A and iron. The results from these tests will not be reported back to you as it will take some time to process the blood.The results will be kept strictly confidential and will not be shared with anyone other than members of our survey team. This information will help the Ministry of Health understand better what problems children in Malawi are experiencing and help them to improve the health and nutrition programs here, which will benefit all children in Malawi. In the last month, has (NAME OF CHILD) received a vitamin A capsule?
Has (NAME OF CHILD) had a fever in the last 2 weeks?
Has (NAME OF CHILD) had a fever in the last 24 hours?
Has (NAME OF CHILD) had diarrhea in the last 2 weeks?
Has (NAME OF CHILD) been ill with malaria in the last 2 weeks?
Have you noticed blood in (NAME OF CHILD)'s urine in the past 2 weeks?
In the last six months, has (NAME OF CHILD) received a blood transfusion?
At what time approximately did (NAME OF CHILD) eat her/his most recent meal?
CHECK 307: AGREED FOR BLOOD TEST Has (NAME OF CHILD) had a cough or breathing problems in the last 2 weeks?
In the last six months, has (NAME OF CHILD) received deworming treatment?
In the last month, has (NAME OF CHILD) taken iron tablets or syrups? As part of this survey we are asking some people to participate in an additional test. We would also like to include your child in an additional test to find out more information about vitamin A in the body. This test will involve giving your child a small amount of liquid to swallow with a snack. We will then have to wait about 4 hours and then take an additional small blood sample.
The results from this test will help the Ministry of Health understand better how well the food fortification program in Malawi is working and if other improvements are necessary. As part of this survey we are asking a parent of some children to allow us to weigh and measure their children and check them for Oedma. If your child has severe acute malnutrition we will refer your child to the nearest facility that can help you. In addition to weighing and measuring your child we would like to take a sample of his/her blood and urine. The tests are safe. Some tests may cause your child slight discomfort, such as taking a blood sample. For all tests, there will be a brand new set of equipment used to take your child's blood and collect their urine, which is clean and completely safe. The equipment will be thrown away after it has been used on your child. With the blood we will test your child for anemia and malaria. Anemia is a serious health problem that usually results from poor nutrition, infection, or chronic disease. Malaria can also be serious and can lead to your child becoming anemic or making the anemia worse. You will be given these results immediately. If needed your child will be referred to a local health facility for treatment. The rest of the blood will be sent to a laboratory to be tested for other vitamins and minerals, such as vitamin A and iron. The results from these tests will not be reported back to you as it will take some time to process the blood.The results will be kept strictly confidential and will not be shared with anyone other than members of our survey team. This information will help the Ministry of Health understand better what problems children in Malawi are experiencing and help them to improve the health and nutrition programs here, which will benefit all children in Malawi. Has (NAME OF CHILD) been ill with malaria in the last 2 weeks?
Have you noticed blood in (NAME OF CHILD)'s urine in the past 2 weeks?
In the last six months, has (NAME OF CHILD) received a blood transfusion?
At what time approximately did (NAME OF CHILD) eat her/his most recent meal?
CHECK 307: AGREED FOR BLOOD TEST

BLUE TOP TUBE (METAL FREE) RECORD THE RESULT OF THE BLUE TOP TUBE BLOOD SAMPLE COLLECTION
Has (NAME OF CHILD) had diarrhea in the last 2 weeks?
Has (NAME OF CHILD) had a cough or breathing problems in the last 2 weeks?
In the last six months, has (NAME OF CHILD) received deworming treatment?
In the last month, has (NAME OF CHILD) received any therapeutic foods, such as PLUMPY NUT [CHIPONDE]?
In the last month, has (NAME OF CHILD) received a vitamin A capsule?
Has (NAME OF CHILD) had a fever in the last 2 weeks?
Has (NAME OF CHILD) had a fever in the last 24 hours?  '3','5',CODE '3','5',CODE '3','5',CODE '3','5',CODE '3','5',CODE '3','5','6' OR '7' 6' OR '7' '6' OR '7' 6' OR '7' '6' OR '7' 6' OR ' As part of this survey we are asking some people to participate in an additional test. We would also like to include your child in an additional test to find out more information about vitamin A in the body. This test will involve giving your child a small amount of liquid to swallow with a snack. We will then have to wait about 4 hours and then take an additional small blood sample.
The results from this test will help the Ministry of Health understand better how well the food fortification program in Malawi is working and if other improvements are necessary.

ADULT RESPONDENT CONSENT FOR ANTHROPOMETRY AND BIOLOGICAL TESTING FROM RESPONDENT
As part of this survey we are asking women from all over this country to allow us to weigh and measure you. In addition to weigh and measuring you we would like to take a sample of your blood and urine. The tests are safe. Some tests may cause you slight discomfort, such as taking a blood sample. For all tests, there will be a brand new set of equipment used to take your blood and collect your urine, which is clean and completely safe. The equipment will be thrown away after it has been used on you.
With the blood we will test you for anemia and malaria. Anemia is a serious health problem that usually results from poor nutrition, infection, or chronic disease. Malaria can also be serious and can lead to you becoming anemic or making the anemia worse. You will be given these results immediately. If needed you will be referred to a local health facility for treatment. The rest of the blood will be sent to a laboratory to be tested for other vitamins and minerals, such as vitamin A and iron. The results from these tests will not be reported back to you as it will take some time to process the blood. The results will be kept strictly confidential and will not be shared with anyone other than members of our survey team. This information will help the Ministry of Health understand better what problems women in Malawi are experiencing and help them to improve the health and nutrition programs here, which will benefit all women in Malawi.

PARENTAL/RESPONSIBLE ADULT CONSENT FOR ANTHROPOMETRY AND BIOLOGICAL TESTING OF A MINOR
(IF REFUSED, SKIP TO 413) As part of this survey we are asking women from all over this country to allow us to weigh and measure you. In addition to weigh and measuring (NAME OF MINOR) we would like to take a sample of (NAME OF MINOR) blood and urine. The tests are safe. Some tests may cause you slight discomfort, such as taking a blood sample. For all tests, there will be a brand new set of equipment used to take HER/HIS blood and collect your urine, which is clean and completely safe. The equipment will be thrown away after it has been used on you.
With the blood we will test (NAME OF MINOR) for anemia and malaria. Anemia is a serious health problem that usually results from poor nutrition, infection, or chronic disease. Malaria can also be serious and can lead to HER/HIM becoming anemic or making the anemia worse. You and (NAME OF MINOR) will be given these results immediately. If needed you (NAME OF MINOR) will be referred to a local health facility for treatment. The rest of the blood will be sent to a laboratory to be tested for other vitamins and minerals, such as vitamin A and iron. The results from these tests will not be reported back to you as it will take some time to process the blood. The results will be kept strictly confidential and will not be shared with anyone other than members of our survey team. This information will help the Ministry of Health understand better what problems women in Malawi are experiencing and help them to improve the health and nutrition programs here, which will benefit all women in Malawi. As part of this survey we are asking women from all over this country to allow us to weigh and measure you. In addition to weigh and measuring you we would like to take a sample of your blood and urine. The tests are safe. Some tests may cause you slight discomfort, such as taking a blood sample. For all tests, there will be a brand new set of equipment used to take your blood and collect your urine, which is clean and completely safe. The equipment will be thrown away after it has been used on you.
With the blood we will test you for anemia and malaria. Anemia is a serious health problem that usually results from poor nutrition, infection, or chronic disease. Malaria can also be serious and can lead to you becoming anemic or making the anemia worse. You will be given these results immediately. If needed you will be referred to a local health facility for treatment. The rest of the blood will be sent to a laboratory to be tested for other vitamins and minerals, such as vitamin A and iron. The results from these tests will not be reported back to you as it will take some time to process the blood. The results will be kept strictly confidential and will not be shared with anyone other than members of our survey team. This information will help the Ministry of Health understand better what problems women in Malawi are experiencing and help them to improve the health and nutrition programs here, which will benefit all women in Malawi.  CODE '2','4',CODE '2','4',CODE '2','4',CODE '2','4',CODE '2','4','6' OR '7' 6' OR '7' '6' OR '7' 6' OR '7' '6' OR '7' 6' OR ' ,'4',CODE '1','4',CODE '1','4',CODE '1','4',CODE '1','4',CODE '1','4','5' OR '7' '5' OR '7' '5' OR '7' '5' OR '7' '5' OR '7' '5' OR ' '3','5',CODE '3','5',CODE '3','5',CODE '3','5',CODE '3','5',CODE '3','5','6' OR '7' 6' OR '7' '6' OR '7' 6' OR '7' '6' OR '7' 6' OR ' As part of this survey we are asking men from all over this country to allow us to weigh and measure you. In addition to weigh and measuring you we would like to take a sample of your blood and urine. The tests are safe. Some tests may cause you slight discomfort, such as taking a blood sample. For all tests, there will be a brand new set of equipment used to take your blood and collect your urine, which is clean and completely safe. The equipment will be thrown away after it has been used on you.
With the blood we will test you for anemia and malaria. Anemia is a serious health problem that usually results from poor nutrition, infection, or chronic disease. Malaria can also be serious and can lead to you becoming anemic or making the anemia worse. You will be given these results immediately. If needed you will be referred to a local health facility for treatment. The rest of the blood will be sent to a laboratory to be tested for other vitamins and minerals, such as vitamin A and iron. The results from these tests will not be reported back to you as it will take some time to process the blood. The results will be kept strictly confidential and will not be shared with anyone other than members of our survey team. This information will help the Ministry of Health understand better what problems men in Malawi are experiencing and help them to improve the health and nutrition programs here, which will benefit all men in Malawi.